Pump



y .23, 1944- r T. H. THOMPSON 2,34%,773

PUMP

Filed Sept. 22, 1941 2 Sheets-Sheet 2 HQA Patented May 23, 1944 Tom B. Thompson, Detroit, Mich, assignor to Builder-Thompson Engineering & Research Corporation, Detroit, Mich., a corporation of Michigan Application September 22, 1941, Serial No. 411,775

7 Claims.

The present invention relates to pumps and specifically to rotary pumps having reciprocating pistons.

Among the objectsof the invention is a variable delivery pump of the type indicated injwhich the delivery may be regulated either automatically by the pressure of the fluid delivery or manually.

Another object is a pump of the type indicated in which the delivery varying or changing means is of simple construction and may be incorporated within the pump unit.

Another object is a multicylinder pump of larg capgcity capable of being built into a small volume un Another object is a reciprocating piston pump in which the piston stroke is variable by means of simple effective means not likely to get out of order, and which may be easily and economically produced.

Still other objects and advantages will be apparent to those skilled in the art upon reference to the following description and the accompanying drawings in which Fig. 1 is a central vertical longitudinal section :hrough a pump embodying the present inven- Fig. 2 is a section on line 2-2 of Fig. 1.

Fig. 3 is a section on line 3-3 of Fig. 1.

Fig. 4. is a section on line 4-4 of Fig. 1.

Fig. 5 is a section on the line 5-5 of Fig. 1.

Figs. 6, 7, 8 and 9 are views in elevation of the several secondary cams.

Fig. 10 is an end view of the cam carrying shaft.

Figs. 11 and 12 are views showingthe relative position of the secondary cams under different conditions.

As indicated in the. drawings, the pump, forming an illustrative embodiment of the invention, consists of a U-shaped housing l5 provided with a suitable cover plate It in which are an inlet "and outlet It. The housing l5 and cover it are each provided with a longitudinally extending bearing portion which together with the pump rotor serve to separate the inlet from the outlet. The two open ends of the U-shaped housing are closed by means of end members which support the pump mechanism.

The rotor 25 consists of a hollow cylinder whose walls are sufficiently thick to provide for the formation therein of a plurality of cylinders 25, there being shown six of these arranged in pairs of which the members are diametrically opposite and in axial alignment, while the several pairs are equiangularly displaced from each other.

Arranged to reciprocate in each pair of cylinders, is a double piston 21, the connecting member of which is provided with a'centrally located circular opening, within which is a rotatable member or cam 28 havinga rectangular opening 23 eccentrically located therein. Suitable antifriction bearings for member 28 are indicated at 28c.

Extending through the several openings 29 is a shaft having at that portion within the several connecting members a plurality of square sections 36, one for each of the members, which shaft is supported at or near its ends in eccentrics or circular cams 31, the latter being fixed to the shaft35 by suitable keys (see Fig. 5).

The cams 31 are themselves rotatably mounted in suitable bearings 31a in other circular cams or eccentrics 33 and i 38, rotatably mounted in bearings 38a. The support for one of said other cams, I38, is a suitable ring 38b, carried by the rotor 25, while the support for cam 38 is a ring or flange 38c forming a part of the end cover The end cover member 40 consists of a plate fitting one end of housing 15 and provided with the circular flange 38c and with a central bore The member 40 is also provided with a diametrically arranged chamber 42 in its outer portion, and in said chamber is located a plunger 43, supported by springs 44 and 45, and provided with an opening in which, with suitable bearings 48, is rotatably arranged the end of shaft 35, this extending beyond the adjacent cam iil and into the bore 4|. Bore H is of suiilcient size to permit considerable movement of the shaft 35 with vertical movements of plunger 43.

The other end of the housing I5 is closed by a member having a central bore through which extends the drive shaft 5|, this being provided with a flange 52, by means of which it may be secured to the rotor 25' as by means of screws The flange portion 52 is, on its inner face, pro vided with a smooth surface 54' against which abuts this end of the shaft 35, a suitable thrust ball 55 or other bearing element'being used.

At its other end, shaft 35 is provided with a thrust bearing such as the ball 56 and a thrust plate 5.1 therefor. The latter is preferably a screw plug serving-also to close the central bore in the end cover 40. .Being a screw plug, this element also serves as a means for adjusting the longitudinal position of shaft :5 and may itself be fixed in adjusted position by prowhich extends the drive shaftli, a dished spring plate 50- is arranged within coverit with its margin between the spacer ring 6! which serves to locate the roller bearing 62 supporting the adjacent end of rotor 25, and a suitable gasket 62' carried by the inner face of cover 50.

, This dished plate 30 is provided with a central opening for shaft 5i and around said opening is fixed in sealed relation a.ring of bearing material 33, preferably "Bakelite backed with a thin layer of neoprene 63a, while carried by shaft 5! is a second ring 64, preferably steel, against which ring 33 bears. A suitable oil retaining ring 63 of conventional construction maybe placed around the shaft II where it emerges from cover 53.

1 It should be noted that each of the piston rods has mounted in it-one of the cams 23 and that, while the two outer ones may be placed over its corresponding square portion of shaft 35, provision must be made for placing the central one in place. Such provision is shown in Fig. '7, which shows this meet the earns 28 to be provided with a triangular insert 23a which may be put vided in those faces adlacentthe center cam, short grooves I23 while the center cam has proiecting from both its faces suitable pins i28a.

Figs. 11 and 12 show the two extreme relative radial positions-of the three cams 23, Fig. 11 showing the inner position in which the cams are concentric and Fig. 12 showing them in their extreme outer position.

In the construction of the, pump, springs 44 i and 45 are selected to correspond to. the maximum pressure which it is desired that the pump shall deliver.

That'is, the strength of springs 44 should be sufiicient, when partly balanced by spring 43, to maintain shaft 35 in its uppermost position so longas there is little or no back pressure on the pistons 21, but allow the shaft 3! to move down toward a position concentric with the rotor. as the delivery pressure increases, and

reaches concentricity when the predetermined maximum pressure has been allowed.

In the operation of the pump, rotation ofthe rotor 23 causes the rotation of cams 23 at double.

the rotor speed and therefore the rotation of the cams 31 at the same speed, while the speed ofrotation of cam 33 will be determined by the position or change of position of shaft 35. So long as the position of shaft 33 is not being its maximum. and the shaft 38 thereby moved down to a position where the shaft 35 and cams 23 are concentric with the rotor, the two cams 31 and 38 neutralize each other and the two rotate as a circular unit. In such case, no reciprocation of the pistons can take place. when, however, the back pressure begins to drop below maximum, the shaft 35 immediately begins to.

assume an eccentric position and the cams 23 likewise begin to assume eccentricity so that the piston reciprocation also resumes.

In changing their relations as above mentioned, all of the several cams move simultaneously with the translative movement of the shaft 35, so that the eccentricity or lift of the cams 28 is always the'same as the eccentricityor lift of the cams at the end of the shaft 35.

This result of this equal lift condition of the two groups of cams is a true straight line reciprocation of the pistons in the cylinders and elimination of all side thrust upon the cylinder walls except that smallvamount due .to friction of the parts.

It is obvious that, as the stroke of the pistons is determined by the position of plunger 43, the

springs 44 may be omitted and a suitable hand operated means substituted therefor. For example, a simple manually operable screw or threaded shaft may be installed in either end of housclaims rather than to the foregoing description to indicate the scope of the invention.

I claim:

1. In a rotary reciprocating piston pump, a

rotor-including a radially arranged cylinder, 9..

piston adapted to be reciprocated therein, eccentric means comprising a shaft and a cam thereon changed. the cam.3l'will rotate at a speed determined by the eccentric position of the axis of shaft 33, but if the shaft is moving up or down,

the cam 33 rotates'at a changing'rate to suit the are arranged exactly opposite and rotate at the same speed.

when back pressure on the pistons has reached for causing straight line reciprocation, said ecrotor including a plurality of cylinders arranged in pairs with the members of a pair diametri- 'cally opposite each other, a unitary piston and connecting member assembly for each pair, and

means for reciprocating said piston assemblies.

when said rotor is driven, said means consisting of a circular cam adapted to coact with each said assembly, a rotatable shaft extending through said cams and fixed against rotation relative thereto, means for normally maintaining said shaft eccentric to said cams. means for as said rotor and means for changing the relation between said shaft and eccentric means whereby to vary the eccentricity of the latter.

4. In a rotary reciprocating piston pump, a rotor provided with a plurality of radially arranged pairs of cylinders, the members oi each pair being diametrically opposite, and the pairs equiangularly spaced, piston for said cylinders. the pistons for each pair being provided with a connecting bar having a central opening, a circular cam mounted for rotation in each of said openings, a rotatable shaft, means for mounting said cams on said shaft in fixed angular relation to each other, means to allow said cams to change their positions relative to the axis of said shaft while maintaining their angular relation, means for supporting said shaft and varying its position in a predetermined straight-line from concentricity with said rotor to any eccentric position up to and including a predetermined maximum eccentricity.

5. In a rotary reciprocating piston pump, a rotor provided with-a plurality of radially arranged pairs of cylinders, the members of each pair being diametrically opposite, and the pairs equiangularly spaced, pistons for said cylinders, the pistons for each pair being provided with a connecting bar having acentral opening, a circular cam mounted for rotation in each of said openings, a rotatable shaft, means for mounting said cams on said shaft in fixed angular relation to each other, means to allow said cams to change their positions relative to the axis of said shaft while maintaining their angular relation, means forsupporting said shaft and varying its position in a predetermined strlilhtline from concentricity with said rotor to any eccentric position up to and including a predetermined maximum eccentricity, said s pp rting means consisting of a circular cam fixed to each end of said shaft and rotatable within another circular cam of equal lift rotatably mounted concentric with said rotor, and resilient means adapted to urge said shaft toward its position of maximum eccentricity.

6. In a rotary reciprocating piston pump, 'a rotor provided with a plurality of cylinders arranged in pairs, the members of a pair being diametrically opposite each other and the pairs being equiangularly displaced, pistons in said cylinders, means for reciprocating said pistons in said cylinders, said mean including a shaft, an eccentric on said shaft for each pair of cylinders, means for fixing the relative angular position of said eccentrics and means for movins. said eccentrics to. a different position relative to the axis of said shaft to thereby change their eccentricity.

7. In a rotary piston pump, a rotor, a rotary shaft arranged with its axis parallel to the axis of the rotor, and carrying piston actuating,

TOM H. THOMPSON.

tricity. 

